Pl. -ici. [L. umbilīcus: see UMBILIC sb.]
1. Anat. The central depression in the abdomen, marking the point of attachment of the umbilical cord; the navel.
[1615. Crooke, Body of Man (1631), 81. They are called Vasa Vmbilicalia, because they passe through the Nauell which is called Vmbilicus.
1693. trans. Blancard’s Phys. Dict. (ed. 2), Umbilicus, the Navel, or Boss in the middle of the Abdomen, to which the Navel-string in a Fœtus is joined.
1728. Chambers, Cycl., s.v. Abdomen, The middle part of the Umbilical [region], is called the Umbilicus, or Navel.]
1799. Med. Jrnl., I. 422. Immediately over the left rectus muscle, at its half intersection below the umbilicus.
1834. J. Forbes, Laennec’s Dis. Chest. (ed. 4), 345. This tumour increased and extended towards the umbilicus.
1876. Bristowe, Th. & Pract. Med. (1878), 650. In which case the general symmetry of the belly is maintained, but the umbilicus is usually deeply sunk.
b. Bot. The part of a seed by which it is attached to the placenta.
1837. P. Keith, Bot. Lex., 89. They are then nourished by means of an umbilicus, which we cannot but regard as an external root.
1857. M. J. Berkeley, Cryptog. Bot., § 108. 135. Acetabularia bears a whorl of threads,… seated on a delicate peduncle, with a few free-branched threads springing from the umbilicus.
1866. Treas. Bot., 1190/1. Umbilicus, the hilum of a seed; the scar formed by its separation from the placenta.
c. transf. The central point.
1897–8. G. T. Stokes, Worthies Irish Ch., i. 5. Killare in the county of Westmeath, formerly regarded as the umbilicus of Ireland.
2. (See quot.) Obs.
1688. R. Holme, Armoury, II. 363/1. An Umbilicus or Navel shell … is a kind of writhen cockle or shell fish wrinkled and turned in on the top like a Navel.
3. Geom. † a. A focus, Obs.
1704. J. Harris, Lex. Techn., I. Umbelicus in an Ellipsis, &c. is that Focus about which the Motion of any Revolving Body is made, and which it respects as its Centre. So that either Focus may be called by this Name.
1728. Chambers, Cycl., s.v. Moon, These smaller [planets] must move in Ellipses having their Umbilici in the Centres of the larger.
b. A point in a surface through which all its lines of curvature pass.
1841. J. R. Young, Math. Dissert., ii. 36. The perplexities and mistakes in the theory of umbilici.
1863. P. Frost & Wolstenholme, Solid Geom., 418. To determine the conditions for an umbilicus. Ibid., 420. To determine the number of umbilici on a surface of the nth degree.
4. A small depression or hollow suggestive of a navel. (Chiefly in special applications.)
a. Bot. 1809. Brown, in Trans. Linnæan Soc. (1811), X. 36. It is not accompanied by the usual position or even uniformity in the situation of the external umbilicus.
1812. New. Bot. Garden, I. 42. The berries are round with a depressed umbilicus.
1845. Florist’s Jrnl. (1846), VI. 196. In the umbilicus alone, whence the powers appear, there are a few small brown rigid setæ rather than spines.
b. Ent. 1819, 1826. [see UMBILICATED a. d].
1828. Stark, Elem. Nat. Hist., II. 380. An indistinct style inclosed in an umbilicus at its extremity.
c. Zool.. 1822. J. Parkinson, Outl. Oryctol., 147. The substance round which the turns are formed, is on the left side of the shell, and terminates at its base; sometimes in a point, and sometimes in a hollow, which is termed an umbilicus.
1851. Woodward, Mollusca, I. 84. The umbilicus is small or obsolete in the typical nautili.
1890. Science-Gossip, XXVI. 242/2. A variety of Helix hortensis … having … traces of white between the bands,… and white continuous over the umbilicus.
d. Ornith. 1878. Dunman, Gloss. Biol. Terms (1889), 152. Umbilicus,… the name given to two apertures (superior and inferior) in the calamus of a bird’s feather.
e. Path. a. 1883. Fagge, Princ. & Pract. Med. (1886), II. 612. The cavity is ‘pocketed’ and shows a central depression or umbilicus.
